Field of the Invention
Exemplary embodiments of the present invention relate to a hybrid power generation system using a supercritical CO2 cycle, and more particularly, to a hybrid power generation system using a supercritical CO2 cycle, which realizes optimal efficiency by applying a supercritical CO2 cycle to a steam cycle as a bottom cycle.
Description of the Related Art
A need to efficiently produce electric power is gradually increased since Korea significantly depends on imported energy sources and constantly suffers from a severe electric power shortage every summer and winter. Moreover, various efforts have been performed in order to reduce generation of pollutants and increase electric power production since activities for reducing generation of pollutants are internationally increased. One of them is a study on a power generation system using supercritical CO2, which utilizes supercritical carbon dioxide as a working fluid, as disclosed in Korean Patent Laid-Open Publication No. 2013-0036180.
The supercritical carbon dioxide simultaneously has a density similar to that of liquid and a viscosity similar to that of gas, thereby enabling the system to be miniaturized and the electric power required for compression and circulation of the fluid to be minimally consumed. In addition, it is easy to handle the supercritical carbon dioxide since the supercritical carbon dioxide has a smaller critical point of 31.4° C. and 72.8 atmospheres, compared to water having a critical point of 373.95° C. and 217.7 atmospheres. When the power generation system using supercritical CO2 is operated at the temperature of 550° C., the system may have about 45% of net power generation efficiency, which is an improved power generation efficiency of 20% or more, compared to an existing steam cycle and the size of a turbo device may be reduced to one several tenth. In addition, the power generation system using supercritical CO2 is mostly operated as a closed cycle which does not discharge the carbon dioxide used for power generation to the outside, thereby significantly contributing to a reduction of pollutant discharge for each country.
However, since it is difficult for the existing power generation system using supercritical CO2 to have a large size more than a certain magnitude, the system may supply only a portion of necessary electric power. In addition, there is a need to efficiently increase electric power production and reduce discharge of pollutants in a coal-fired thermal power generation system.
Accordingly, in order to resolve these problems, there is a need to improve the power generation system using supercritical CO2 and the coal-fired thermal power generation system and to efficiently enhance electric power production.